1. Field of the Invention
The present invention relates to a jack assembly, and more particularly to a jack assembly that may be lifted rapidly.
2. Description of the Related Art
A conventional jack in accordance with the prior art shown in FIGS. 1-4 comprises a base 10, a push seat 14, and an outer cylinder 11 and an inner cylinder 12 mounted between the base 10 and the push seat 14. An inner oil chamber is formed in the inner cylinder 12, and an oil storage chamber xe2x80x9cAxe2x80x9d filled with hydraulic oil is formed between the outer cylinder 11 and the inner cylinder 12. A lifting column 13 is mounted in the inner oil chamber of the inner cylinder 12, and has a first end provided with a piston 131, and a second end that may be protruded outward to perform a lifting action.
The base 10 is provided with a main oil path 102, and has an end face provided with an oil suction hole 101 connected to the lower end of the main oil path 102. An anti-reverse ball 31 is mounted in the lower end of the main oil path 102 to block the main oil path 102, and is pushed by a post 32. A main ball 33 is mounted in the mediate portion of the main oil path 102, and is pushed by an adjusting screw 34. An oil inlet hole 106 located above the main ball 33 is formed in the inner wall of the main oil path 102, and is connected to the inner oil chamber as shown in FIG. 3.
An oil hole 103 located above the anti-reverse ball 31 is formed in the inner wall of the main oil path 102, and is connected to a return oil path 104 as shown in FIG. 4. A spring 42 is mounted in the return oil path 104, and is pushed by a screw 41. A pusher 43 is mounted on the lower end of the spring 42, and has a distal end provided with a ball 44 which is placed in an oil hole that is connected to the oil hole 103. The inner wall of the return oil path 104 is formed with a return oil hole 105 that is connected to the oil storage chamber xe2x80x9cAxe2x80x9d.
Thus, when the pump 2 mounted on the base 10 perform a suction action through the oil hole 103, the hydraulic oil contained in the oil storage chamber xe2x80x9cAxe2x80x9d is sucked into the lower end of the main oil path 102 through the oil suction hole 101, to push away the anti-reverse ball 31, so that the hydraulic oil may be sucked into the oil hole 103 and the pump 2. Then, when the pump 2 is pushed and compressed, the hydraulic oil may be pushed into the main oil path 102 without returning to the oil storage chamber xe2x80x9cAxe2x80x9d by stopping of the anti-reverse ball 31. The hydraulic oil then pushes the main ball 33 upward, so that the hydraulic oil may flow through the oil inlet hole 106 into the inner chamber. The pump 2 may be operated continuously, so that the hydraulic oil may be pushed into the inner chamber successively, to force the lifting column 13 in the inner oil chamber of the inner cylinder 12 to move outward so as to perform a lifting action.
However, the amount of the hydraulic oil that is pushed into the inner chamber at each time is very small, and the inner chamber has a large cross-sectional area, so that the lifting velocity of the lifting column 13 is very slow, thereby consuming working time, and thereby causing inconvenience to the user.
The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional jack.
The primary objective of the present invention is to provide a jack assembly that may be lifted rapidly. A lifting column is mounted in the inner cylinder. A secondary shaft formed with an oil hole is mounted in the lifting column, and has a distal end screwed into an axial hole in the base. The main oil path is provided with a lower ball, and an upper ball, the main oil path is formed with a first oil hole located above the lower ball and connected to the oil hole of the secondary shaft, and formed with a second oil hole located above the upper ball and connected to the inner oil chamber. The hydraulic oil pushes away the lower ball, so that the hydraulic oil may flow through the first oil hole into the oil hole of the secondary shaft, so that the lifting column that has not worked may be lifted rapidly. The lifting column works to increase the pressure of the hydraulic oil of the main oil path, so that the hydraulic oil flows through the second oil hole into the inner oil chamber of the inner cylinder, so that the lifting column may have a sufficient lifting force to lift an object.
In accordance with the present invention, there is provided a jack assembly that may be lifted rapidly, comprising: a base, a push seat, and an outer cylinder and an inner cylinder mounted between the base and the push seat, an inner oil chamber formed in the inner cylinder, an oil storage chamber formed between the outer cylinder and the inner cylinder, a lifting column mounted in the inner cylinder, and having a distal end provided with a piston, the base provided with a main oil path, and having an end face provided with an oil suction hole connected to the oil storage chamber and connected to a lower end of the main oil path, an anti-reverse ball mounted in the lower end of the main oil path to block the main oil path, and is pushed by a post, an oil hole located above the anti-reverse ball being formed in the inner wall of the main oil path, and connected to a return oil path; wherein:
a lower ball is mounted in a mediate portion of the main oil path, and is pushed by a first spring, an upper end of the first spring is provided with an upper ball, the upper ball is provided with a push post which is pushed by a second spring, an upper end of the second spring is pushed by an adjusting screw, the main oil path has an inner wall formed with a first oil hole that is located above the lower ball, the first oil hole is connected to an oil hole of a center of a secondary shaft that is mounted in the lifting column, the inner wall of the main oil path is formed with a second oil hole that is located above the upper ball, and is connected to the inner oil chamber; and wherein:
hydraulic oil in the oil storage chamber pushes away the lower ball, so that the hydraulic oil may flow through the first oil hole into the oil hole of the secondary shaft, the hydraulic oil may push the lifting column by means of a smaller cross-sectional area of an axial hole for receiving the secondary shaft, so that the lifting column that has not worked may be lifted rapidly, thereby shortening the working stroke, when lifting of the lifting column is stopped, the lifting column works and a pressure of the hydraulic oil of the main oil path is increased largely, whereby the upper ball is pushed away, so that the hydraulic oil flows through the second oil hole into the inner oil chamber of the inner cylinder, the inner oil chamber of the inner cylinder has a larger cross-sectional area, so that the lifting column may have a sufficient lifting force to lift an object.
The base has another end face provided with an anti-reverse valve, so that the hydraulic oil in the oil storage chamber may be introduced into the inner oil chamber of the inner cylinder, and hydraulic oil in the inner oil chamber of the inner cylinder cannot flow into the oil storage chamber.
The anti-reverse valve includes a screw seat, a ball, and a spring.
The anti-reverse valve has an oil hole formed in the end face of the base, the oil hole has a first end connected to a conducting pipe that is connected to the oil storage chamber, and a second end connected to the inner oil chamber of the inner cylinder.
Thus, during a non-work stroke of the lifting column, a suction action applied on the inner oil chamber of the inner cylinder forces hydraulic oil to flow through the conducting pipe, the anti-reverse valve and the oil hole to enter the inner oil chamber of the inner cylinder, so that the lifting column may be conveniently lifted rapidly.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.